Fuel composition for internal-combustion engines containing trialkylamine

ABSTRACT

Disclosed herein is a fuel composition for internal combustion engines comprising a trialkylamine. Specifically, the fuel composition for internal combustion engines is prepared by adding a tertiary amine of trialkylamine to a gasohol which is a mixture of anhydrous or hydrous ethanol and naphtha, wherein the hydrous ethanol contains up to 10% by volume of water and shows an improved inhibition of a phase separation and corrosion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a fuel composition for internal combustion engines containing a trialkylamine. More specifically, the present invention relates a fuel composition for internal combustion engines for inhibiting phase separation and corrosion, which is prepared by adding tertiary amine of trialkylamine to a gasohol which is a blend of anhydrous or hydrous ethanol and naphtha, wherein the hydrous ethanol contains up to 10% by volume of water.

2. Background of the Related Art

Depletion of fossil fuels and environmental pollution become serious all over the world. Environmental problems, such as increase of air pollution by excessive use of fossil fuels, global warming due to increased level of carbon dioxide and the like, come up as a sharp issue. In particular, since United Nations Framework Convention on Climate Change and Kyoto Protocol are coming into effect, development of alternative fuels is needed urgently so as to comply with the international environment regulation for the inhibition of carbon oxide emission.

According to this international current, bioalcohols are developing as an alternative fuel, based on the study that alcohol-containing fuel reduces the emission of carbon oxide and nitrogen oxide (Johnson R. T., Stoffer J. O., Soc. Automot. Eng. (Spec. Publ.) 1983. S.P. 542, 91-104).

Ethanol can be industrially produced in petrochemistry and also extracted from biomass such as plant. Further, ethanol has an advantage in that it can be used as fuel for the internal combustion engine including the conventional gasoline engine without changing the structure of the internal combustion engine. Now, in U.S and Canada, gasohol which is a blend of about 90% of gasoline and about 10% of anhydrous ethanol is used in some automobiles. In particular, the ethanol blended with gasoline is a bioethanol extracted from plants and spotlighted as an environmentally friendly and inexhaustible fuel resource. However, in case that the alcohol which is obtained by fermenting plants is distilled so as to remove the water contained in the alcohol, when the concentration of ethanol becomes 95% by volume, the purification process can not go forward any more due to an azeotropic phenomenon. Thus, an additive such as pentane is added to a second distillation tower to carry out the azeotropic distillation again. Although highly pure ethanol can be obtained through this process, the cost for purification is increased and the energy for distillation is wasted. Meanwhile, a very small amount of moisture improves the octane number. If there are no problems in phase separation and corrosion, in the aspect of economy and octane number it is preferred that the hydrous ethanol which is distilled at the azeotropic point is used for the preparation of gasohol. Even though anhydrous alcohol is used for the gasohol, it absorbs the moisture in the atmosphere during storage or delivery and, thus, the hydrophilic alcohol is separated from the hydrophobic hydrocarbon which is a major component of gasoline at a low temperature. Further, the gasohol comprising the water-absorbed, anhydrous ethanol has a phase separation at a temperature higher than that of the gasohol comprising the hydroud ethanol which is distilled at azeotropic point.

An agent for inhibiting a phase separation, for example, N,N-bis(hydroxyalkyl)alkylamide disclosed in U.S. Pat. No. 4,428,754 has been used, but its efficiency was not good. Further, U.S. Pat. No. 4,541,836 discloses a use of higher alcohol as a phase separation inhibitor, but the higher alcohol does not show a corrosion preventing effect. A primary amine compound was effective in inhibiting a phase separation in a hydrochloric solution (Electrochimica Acta Vol 42, No 3, pp 455-459, 1997), but in the study of corrosion of copper metal in gasohol copper-releasing was observed.

Up to now, the use of tertiary amine in the preparation of fuel such as gasohol, etc. has been limited to that as a reaction catalyst in the process for the preparation of amide compounds contained in a fuel composition.

Under these circumstances, the present inventors have found that, when tertiary amine of trialkylamine is added to a gasohol or diesel oil containing an anhydrous or hydrous bioethanol, the tertiary amine inhibits a phase separation and corrosion and is compatible with the typical gasoline component of hydrocarbon, which make it possible to develop an alcohol fuel for internal combustion engines which can be directly applied to the engine without changing the design of engine.

BRIEF SUMMARY OF THE INVENTION

An object of the present invention is to provide a fuel composition for internal combustion engines which can inhibit a phase separation and corrosion, comprising an anhydrous ethanol or hydrous ethanol containing up to 10% by volume of water and a naphtha.

To accomplish the above object of the present invention, the tertiary amine of trialkylamine is added to a gasohol comprising an anhydrous ethanol or hydrous ethanol containing up to 10% by volume of water and a naphtha, resulting in providing a fuel composition having the effect of phase separation inhibition and corrosion prevention.

The fuel composition for internal combustion engines according to the present invention can inhibit a phase separation and corrosion, which are problems in a fuel of liquid-phase hydrocarbon-ethanol blend, and satisfy the standards which have been required for the conventional gasoline.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows photographs presenting the results of corrosion test to copper plate and iron nail in a fuel of liquid-phase hydrocarbon blended with ethanol, wherein

[iron nail: iron component; weight: about 2.5±0.1 g; average length: about 5 cm; average diameter: 0.3 cm]

[copper plate: copper component; weight: about 12±0.5 g; average length: about 7.2 cm; average diameter: 1.2 cm, average thickness: 0.1 cm]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention relates to a fuel composition for internal combustion engines for inhibiting a phase separation and corrosion, which is prepared by adding a trialkylamine which is a tertiary amine to a gasohol which is a blend of anhydrous or hydrous ethanol and naphtha, wherein the hydrous ethanol contains up to 10% by volume of water.

The trialkylamine used in the present fuel composition is multifunctional in inhibiting a phase separation and corrosion. A primary amine can be also used for preventing a phase separation, but its effect is lower than that of the tertiary amine. Isobutyl alcohol shows a good effect in inhibiting a phase separation, but has no effect in corrosion prevention.

The tertiary amine of trialkylamine used in the present invention is represented by the formula 1:

wherein R, R′ and R″ are the same or different and are alkyl groups having from 1 to 18 carbon atoms, and the carbon number of each of the substituents is identical or different.

An example of the trialkylamine is represented by the formula 2:

N,N-diethyloctane-1-amine is represented by the formula 3:

More specifically, examples of trialkylamine which is a tertiary amine include, but are not limited to, trimethylamine, triethylamine, tripropylamine, tributylamine, tripentylamine, N,N-diethyl oleyl amine, N,N-diethyloctylamine, and other tertiary amine having alkyl groups each of which has a different number of carbon atoms, and triethylamine, tripropylamine, N,N-diethyloleylamine, N,N-dimethyloleylamine, N,N-diethyloctan-1-amine and N,N-dimethyloctan-1-amine is more preferred. The tertiary amine can be prepared by reacting monoalkylamine with alcohol such as ethanol or methanol with a catalyst (gamma alumina) at a high temperature of 200 to 300° C. in a vapor phase to thereby alkylate the monoalkylamine (Tetrahedron Letters 40. 3689-3592, 1999).

The fuel composition for internal combustion engines according to the present invention can be prepared by blending a trialkylamine with a gasohol at ambient temperature under atmospheric pressure, wherein the gasohol is a blend of 5 to 95% by volume of ethanol containing 0 to 10% water and the balance amount of naphtha and the trialkylamine is added in an amount of 0.01 to 10% by volume, based on 100% by volume of gasohol.

The liquid hydrocarbon used in the present invention comprises as a major component C4-C15 paraffin-based hydrocarbon and a small amount of cycloparaffin-based hydrocarbon and the like is contained, which is called gasoline or naphtha. The naphtha can be contained in an amount of 5 to 95% by volume based on the total amount of the gasohol of the present invention.

The ethanol used in the present invention can be an anhydrous or a hydrous bioethanol which comprises up to 10% by volume of water.

The fuel composition can further comprise as other additives higher alcohol such as isopropanol, isobutanol, octanol and the like which assists the function of phase separation inhibition. The higher alcohol can be contained in an amount of 0.1 to 5% by volume based on the total amount of the fuel composition.

Hereinafter, the present invention will be illustrated in details with reference to the following examples.

Test 1: Phase Separation Inhibition

As shown in Table 1 below, the naphtha and the fermented ethanol with a purity of 95% were mixed with the tertiary amine of triethylamine, tripropylamine, tributylamine or triisobutylamine which is a phase separation inhibitor, or isobutylalcohol which is well known in the art as a phase separation inhibitor in an amount of 0, 1, 2, 3, 4 and 5% v/v at ambient temperature of 18 to 15° C. under atmospheric pressure, and kept in a freezer which can be lowered up to −15° C. for 20 to 30 minutes to observe the temperature of phase separation. The result is indicated in Table 1, wherein E10 represents the mixture of naphtha and fermented ethanol (purity: 95%) and phase separation inhibitor in the volume ratio of 90:10:5 and E51 represents the mixture of naphtha and fermented ethanol (purity: 95%) and phase separation inhibitor in the volume ratio of 49:51:5. The known phase separation inhibitor of isobutylalcohol showed a good inhibition of phase separation, but did not provide anti-corrosion effect.

TABLE 1 Phase separation temperature [° C.] Tri- tri- tri- triiso- Iso- ethyl- propyl- butyl- butyl- butyl- amine amine amine amine alcohol E10 E51 E10 E51 E10 E51 E10 E51 E10 E51 r.t. 11 r.t. 11 r.t. 11 r.t. 11 r.t. 11 r.t. 7 r.t. 8 r.t. 11 r.t. 11 r.t. 5 r.t. 1 r.t. 4 r.t. 9 r.t. 12 r.t. −1 r.t. −5 r.t. 0 r.t. 8 r.t. 12 15 −6 r.t. −10 r.t. −3 r.t. 5 r.t. 12 0 −9 r.t. −15 ↓ r.t. −9 r.t. 3 r.t. 12 −9 r.t.: room temperature

As observed in the result of Table 1, the use of trialkylamine according to the present invention resulted in a good phase separation inhibition and the temperature of phase separation was varied according to the content of naphtha, fermented ethanol and phase separation inhibitor. From the above result, the fuel composition of naphtha, fermented ethanol and phase separation inhibitor mixed with the volume ratio of 49:51:5 showed the highest inhibition effect of phase separation.

EXAMPLE 1

The fuel of liquid hydrocarbon-ethanol blend was prepared by mixing naphtha, fermented ethanol (purity: 95%) and triethylamine in the volume ratio of 49:51:4 at ambient temperature under atmospheric pressure.

EXAMPLE 2

The fuel of liquid hydrocarbon-ethanol blend was prepared by mixing naphtha, fermented ethanol (purity: 95%) and tripropylamine in the volume ratio of 49:51:4 at ambient temperature under atmospheric pressure.

EXAMPLE 3

The fuel of liquid hydrocarbon-ethanol blend was prepared by mixing naphtha, fermented ethanol (purity: 95%) and tributylamine in the volume ratio of 49:51:4 at ambient temperature under atmospheric pressure.

EXAMPLE 4

The fuel of liquid hydrocarbon-ethanol blend was prepared by mixing naphtha, fermented ethanol (purity: 95%) and triisobutylamine in the volume ratio of 49:51:4 at ambient temperature under atmospheric pressure.

COMPARATIVE EXAMPLE 1

The fuel of liquid hydrocarbon-ethanol blend was prepared by mixing naphtha, fermented ethanol (purity: 95%) and the primary amine of octylamine in the volume ratio of 49:51:4 at ambient temperature under atmospheric pressure.

COMPARATIVE EXAMPLE 2

The fuel of liquid hydrocarbon-ethanol blend was prepared by mixing naphtha, fermented ethanol (purity: 95%) and the primary amine of oleylamine in the volume ratio of 49:51:4 at ambient temperature under atmospheric pressure.

Test 2: Corrosion Prevention

The test was carried out to copper plates and iron nails by using the fuels prepared in Examples 1 to 4 and Comparative Examples 1 and 2 and the result is indicated in Table 2. The fuel of liquid hydrocarbon-ethanol blend prepared according to the same conditions without adding the phase separation inhibitor and anti-corrosive agent was compared as a control group.

Parameter measured: the weight change after storing specimen for 7 days

Procedures: The surfaces of iron specimen (nail, length: 5 cm) and copper specimen (plate, size: C1100R, length: 7.2 cm) were rubbed with a sand paper and the specimens were washed with acetone and weighed. Two-thirds of each specimen was soaked in bottles containing the fuel which comprises the above agent added in an amount of 5% by volume based on the liquid hydrocarbon-ethanol blend and kept it at a temperature of 50° C. for 7 days. The specimen was removed from the bottle and the change of weight was measured.

TABLE 2 Change of Change of Change of color (based weight weight on two-thirds of after 7 after 7 Example No. Specimen height) days [g] days [%] Control Iron Production of brown 0.001 0.040 rust Control Copper Upper part: changed 0.004 0.034 into brown, lower part: changed into orange Comparative Iron No changed 0.001 −0.020 Example 1 Comparative Copper All changed into −0.007 −0.060 Example 1 brown Comparative Iron No changed 0.000 0.000 Example 2 Comparative Copper Upper part: changed −0.003 −0.026 Example 2 into brown, lower part: changed into orange Example 1 Iron No changed 0.000 0.000 Example 1 Copper No changed −0.001 −0.009 Example 2 Iron No changed 0.000 0.000 Example 2 Copper Upper part: changed 0.000 0.000 into orange, lower part: clean Example 3 Iron No changed 0.000 0.000 Example 3 Copper Upper part: changed −0.002 −0.016 into orange, lower part: clean Example 4 Iron No changed 0.000 0.000 Example 4 Copper Upper part: changed −0.002 −0.017 into orange, lower part: clean

The weight change after 7 days[g] and the percentage of weight change after 7 days [%] are calculated by Equations 1 and 2 below:

[Equation 1]

Weight change after 7 days [g]=(weight after soaking for 7 days−weight before soaking)   (1)

[Equation 2]

Percentage of weight change after 7 days [%]=[(weight after soaking for 7 days−weight before soaking)/weight before soaking]×100   (2)

From the result shown in Table 2, Examples 1 to 4 which comprise the trialkylamine additive showed a low weight change, compared with the control group which comprises only fuel without any additives and comparative Examples 1 and 2 which comprise the primary alkylamine additive.

While the present invention has been described with reference to the particular illustrative embodiments, it is not to be restricted by the embodiments but only by the appended claims. It is to be appreciated that those skilled in the art can change or modify the embodiments without departing from the scope and spirit of the present invention. 

1. A fuel composition for internal combustion engines which comprises a gasohol and a trialkylamine of formula 1:

wherein R, R′ and R″ are, independently of each other, a saturated or unsaturated C1-C18 alkyl group and the carbon number of each of the substituents is identical or different, wherein the gasohol is a blend of anhydrous or hydrous ethanol and naphtha and the hydrous ethanol contains up to 10% by volume of water, and wherein the trialkylamine is added in an amount of 0.01 to 10% by volume, based on 100% by volume of gasohol.
 2. The fuel composition of claim 1, wherein the anhydrous or hydrous ethanol is blended with naphtha in the volume ratio of 1:19 to 19:1.
 3. The fuel composition of claim 1, wherein the trialkylamine is triethylamine.
 4. The fuel composition of claim 1, wherein the trialkylamine is tripropylamine.
 5. The fuel composition of claim 1, wherein the trialkylamine is N,N′-diethyloleylamine or N,N-dimethyloleylamine.
 6. The fuel composition of claim 1, wherein the trialkylamine is N,N′-diethyloctan-1-amine or N,N-dimethyloctan-1-amine.
 7. The fuel composition of claim 1, wherein the trialkylamine is for the inhibition of phase separation.
 8. The fuel composition of claim 1, wherein the trialkylamine is for the prevention of corrosion. 